1. Field of the Invention
The present invention relates to a telemanipulator (or remote handling device) of small bulk.
The invention is of particular application in all fields where it is necessary to work at a distance in a restricted space, such as inside the passages of nuclear reactors where operations are carried out under a protective covering of water.
2. Description of the Prior Art
The supervision and maintenance of nuclear reactors and the equipment surrounding them necessitates the use of manipulators capable of penetrating inside narrow passages and carrying out various operations therein. To be effective, these manipulators must be capable of substantially reproducing the same movements as a human arm and of possessing substantially the same degrees of freedom. Thus, they must be capable of pivoting on themselves around their longitudinal axes, of bending at different pivot points, of orienting their ends and of opening or closing the pincers or tongs with which they are equipped. All these movements being controlled at a distance necessitates the presence of numerous devices which have to be housed inside the articulated elements of the manipulator arm.
One type of known pneumatic or hydraulic manipulator is described in French Pat. No. 1,500,113/92845 which discloses arm elements articulated together by means of ball joints which are actuated by jacks arranged along said elements. These jacks present lateral protuberances along the arm elements which considerably increase the cross-section of the arm. In addition, because of the relatively limited travel distance of the rod of said jacks, the angular displacement of the elements with respect to one another is rather restricted.
Furthermore, this type of apparatus uses to fluids (water, oil) for the operation of the jacks, which on the one hand may be dangerous when used in nuclear reactors, and on the other hand, necessitate the use of a large number of ducts each associated with a given jack.
Another type of manipulator using mechanical gearing control is described in French Pat. No. 1,459,250. In this apparatus, the rotational axes of the gears are at right angles to the longitudinal axis of the element which houses them and since the pinions necessarily have a large diameter in order to be able to transmit relatively high torque, the diameter and length of the arm are large. In addition, the disclosed arrangement of the gear wheels does not fully lend itself to sound sealing, with the result that the manipulator cannot operate in a liquid, such as under water in the passages of nuclear reactors.
Finally as regards the terminal tool of a manipulator, French Pat. No. 1,508,128 describes an example of a known one including three electric motors housed in an arm element used to axially displace, to rotate and to open or close the gripping members of a pair of tongs.
This assembly though compact, is very complex and has the major drawback of requiring of electric supply rings on which collector strips rub.
It is an object of the invention to provide a telemanipulator which overcomes the abovementioned drawbacks.
It is another object of the invention to provide a compact telemanipulator with a large number of instruments confined in a restricted space.
It is a further object to provide a telemanipulator which is capable of carrying out the same movements as a human arm while minimizing bulk, thus enabling it to penetrate into very narrow passages.
Yet another object of the invention is to provide a telemanipulator in which the combination of a choice and arrangement of arm element and tool drive means produces a telemanipulator which is compact, accurate, powerful for its size and particularly effective for operation in restricted spaces.
Other objects and advantages of the invention will become apparent from the description which follows.